I have experienced this issue on brand new Windows Server 2012 R2 Virtual Machine on Hyper-V. After installation of the WSUS role, the post configuration wizard fails with “Fatal Error: Attempted to perform an unauthorized operation”

This is relate to folder permission and for fix this issue set below permissions in respective folders. *Local Domain Name is blocked by a black square.

WSUS Content Folder Permission

D:\WSUS

NETWORK SERVICE = Full Control

D:\WSUS\WsusContent

NETWORK SERVICE = Full Control
Creator Owner = Special permissions
System = Full Control
Administrators (<WSUSServerName>\Administrators) = Full Control
Users (<DomainName>\Users) = Read & Execute, List folder contents, Read, Special permissions

Folder:

%ProgramFiles%\Update Services\LogFiles

After setting up above permissions restart the server and try to rerun the post installation wizard. It should complete without any issue.